[tip: irq/core] genirq: Cache the condition for /proc/interrupts exposure
From: tip-bot2 for Thomas Gleixner
Date: Tue May 26 2026 - 10:36:52 EST
The following commit has been merged into the irq/core branch of tip:
Commit-ID: 4892e5e71ec9c942293cea7fd26e0c76179211ed
Gitweb: https://git.kernel.org/tip/4892e5e71ec9c942293cea7fd26e0c76179211ed
Author: Thomas Gleixner <tglx@xxxxxxxxxx>
AuthorDate: Sun, 17 May 2026 22:02:19 +02:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxx>
CommitterDate: Tue, 26 May 2026 16:21:13 +02:00
genirq: Cache the condition for /proc/interrupts exposure
show_interrupts() evaluates a boatload of conditions to establish whether
it should expose an interrupt in /proc/interrupts or not.
That can be simplified by caching the condition in an internal status flag,
which is updated when one of the relevant inputs changes.
The irq_desc::kstat_irq check is dropped because visible interrupt
descriptors always have a valid pointer.
As a result the number of instructions and branches for reading
/proc/interrupts is reduced significantly.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxx>
Tested-by: Michael Kelley <mhklinux@xxxxxxxxxxx>
Reviewed-by: Dmitry Ilvokhin <d@xxxxxxxxxxxx>
Reviewed-by: Radu Rendec <radu@xxxxxxxxxx>
Link: https://patch.msgid.link/20260517194931.680943749@xxxxxxxxxx
---
include/linux/irq.h | 1 +
kernel/irq/chip.c | 2 ++
kernel/irq/internals.h | 2 ++
kernel/irq/manage.c | 8 +++++++-
kernel/irq/proc.c | 15 +++++++++++----
kernel/irq/settings.h | 13 +++++++++++++
6 files changed, 36 insertions(+), 5 deletions(-)
diff --git a/include/linux/irq.h b/include/linux/irq.h
index efa514e..f485369 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -103,6 +103,7 @@ enum {
IRQ_DISABLE_UNLAZY = (1 << 19),
IRQ_HIDDEN = (1 << 20),
IRQ_NO_DEBUG = (1 << 21),
+ IRQ_RESERVED = (1 << 22),
};
#define IRQF_MODIFY_MASK \
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 6c9b1dc..2d283d1 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -1007,6 +1007,7 @@ __irq_do_set_handler(struct irq_desc *desc, irq_flow_handler_t handle,
WARN_ON(irq_chip_pm_get(irq_desc_get_irq_data(desc)));
irq_activate_and_startup(desc, IRQ_RESEND);
}
+ irq_proc_update_valid(desc);
}
void __irq_set_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
@@ -1067,6 +1068,7 @@ void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
trigger = tmp;
irqd_set(&desc->irq_data, trigger);
+ irq_proc_update_valid(desc);
}
}
EXPORT_SYMBOL_GPL(irq_modify_status);
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index db359ac..e5f3d31 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -123,6 +123,7 @@ extern void register_irq_proc(unsigned int irq, struct irq_desc *desc);
extern void unregister_irq_proc(unsigned int irq, struct irq_desc *desc);
extern void register_handler_proc(unsigned int irq, struct irqaction *action);
extern void unregister_handler_proc(unsigned int irq, struct irqaction *action);
+void irq_proc_update_valid(struct irq_desc *desc);
#else
static inline void register_irq_proc(unsigned int irq, struct irq_desc *desc) { }
static inline void unregister_irq_proc(unsigned int irq, struct irq_desc *desc) { }
@@ -130,6 +131,7 @@ static inline void register_handler_proc(unsigned int irq,
struct irqaction *action) { }
static inline void unregister_handler_proc(unsigned int irq,
struct irqaction *action) { }
+static inline void irq_proc_update_valid(struct irq_desc *desc) { }
#endif
extern bool irq_can_set_affinity_usr(unsigned int irq);
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 8863b2d..7eb07e3 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1802,6 +1802,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
__enable_irq(desc);
}
+ irq_proc_update_valid(desc);
raw_spin_unlock_irqrestore(&desc->lock, flags);
chip_bus_sync_unlock(desc);
mutex_unlock(&desc->request_mutex);
@@ -1906,6 +1907,7 @@ static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id)
desc->affinity_hint = NULL;
#endif
+ irq_proc_update_valid(desc);
raw_spin_unlock_irqrestore(&desc->lock, flags);
/*
* Drop bus_lock here so the changes which were done in the chip
@@ -2047,6 +2049,8 @@ static const void *__cleanup_nmi(unsigned int irq, struct irq_desc *desc)
irq_shutdown_and_deactivate(desc);
}
+ irq_proc_update_valid(desc);
+
if (action)
unregister_handler_proc(irq, action);
kfree(action);
@@ -2433,8 +2437,10 @@ static struct irqaction *__free_percpu_irq(unsigned int irq, void __percpu *dev_
*action_ptr = action->next;
/* Demote from NMI if we killed the last action */
- if (!desc->action)
+ if (!desc->action) {
desc->istate &= ~IRQS_NMI;
+ irq_proc_update_valid(desc);
+ }
}
unregister_handler_proc(irq, action);
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index d5b8126..cc9c7c9 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -440,6 +440,16 @@ void init_irq_proc(void)
register_irq_proc(irq, desc);
}
+void irq_proc_update_valid(struct irq_desc *desc)
+{
+ u32 set = _IRQ_PROC_VALID;
+
+ if (irq_settings_is_hidden(desc) || irq_desc_is_chained(desc) || !desc->action)
+ set = 0;
+
+ irq_settings_update_proc_valid(desc, set);
+}
+
#ifdef CONFIG_GENERIC_IRQ_SHOW
int __weak arch_show_interrupts(struct seq_file *p, int prec)
@@ -516,10 +526,7 @@ int show_interrupts(struct seq_file *p, void *v)
guard(rcu)();
desc = irq_to_desc(i);
- if (!desc || irq_settings_is_hidden(desc))
- return 0;
-
- if (!desc->action || irq_desc_is_chained(desc) || !desc->kstat_irqs)
+ if (!desc || !irq_settings_proc_valid(desc))
return 0;
seq_printf(p, "%*d:", prec, i);
diff --git a/kernel/irq/settings.h b/kernel/irq/settings.h
index 00b3bd1..0a0c027 100644
--- a/kernel/irq/settings.h
+++ b/kernel/irq/settings.h
@@ -18,6 +18,7 @@ enum {
_IRQ_DISABLE_UNLAZY = IRQ_DISABLE_UNLAZY,
_IRQ_HIDDEN = IRQ_HIDDEN,
_IRQ_NO_DEBUG = IRQ_NO_DEBUG,
+ _IRQ_PROC_VALID = IRQ_RESERVED,
_IRQF_MODIFY_MASK = IRQF_MODIFY_MASK,
};
@@ -34,6 +35,7 @@ enum {
#define IRQ_DISABLE_UNLAZY GOT_YOU_MORON
#define IRQ_HIDDEN GOT_YOU_MORON
#define IRQ_NO_DEBUG GOT_YOU_MORON
+#define IRQ_RESERVED GOT_YOU_MORON
#undef IRQF_MODIFY_MASK
#define IRQF_MODIFY_MASK GOT_YOU_MORON
@@ -180,3 +182,14 @@ static inline bool irq_settings_no_debug(struct irq_desc *desc)
{
return desc->status_use_accessors & _IRQ_NO_DEBUG;
}
+
+static inline bool irq_settings_proc_valid(struct irq_desc *desc)
+{
+ return desc->status_use_accessors & _IRQ_PROC_VALID;
+}
+
+static inline void irq_settings_update_proc_valid(struct irq_desc *desc, u32 set)
+{
+ desc->status_use_accessors &= ~_IRQ_PROC_VALID;
+ desc->status_use_accessors |= (set & _IRQ_PROC_VALID);
+}